Launch Configurations

Launch configurations define environment in a way similar to Project Properties but in a form that can be applied to an individual file through File Properties, in the creation of named entry points, and for running the Python Shell.

They are managed from Launch Configurations in the Project menu. Use the icons or right click to create, edit, duplicate, or delete items.

Launch configurations contain the following properties. For all of these, environment variable references may be used, as described in Environment Variable Expansion:

Python Tab

Python Executable selects the Python that should be used when running code with this launch configuration. This can be set to Use project setting to use the setting in Project Properties.

Use default uses Python found on the PATH, or if none is found there then the latest version found anywhere on the system. Use Command Line to enter any command that invokes Python with all provided arguments. This is the value of sys.executable (after import sys) in the selected Python. A list of all found Python installations is given in the drop down to the right of the entry area.

To use an environment set up by virtualenv or Anaconda, choose Activated Env to enter the full path to activate or activate.bat for the selected environment. The drop down menu to the right of this field lists recently used and automatically found environments. This will not work if the full path to the activate script contains spaces. In that case, use the Command Line option as described above.

In Wing Pro, this property can tell Wing to run Python on a container or remote host. On a container, some of the other properties listed below (as noted) are ignored since the container defines the runtime environment. On a remote host, the default directory used for other fields in Project Properties, and for adding files and directories to the project, will be the base directory defined for the selected remote host.

When this property invokes Anaconda Python, Wing will automatically run conda activate base before it starts Python. This is needed to avoid failure to import some modules as a result of missing environment. See About Anaconda Environments in the Anaconda How-To for details.

Python Path sets the PYTHONPATH that is used by Python to locate modules that are imported with the import statement. By default this uses the path set in Project Properties. When Use default is selected, the PYTHONPATH environment variable inherited by Wing at startup is used instead. Otherwise, when Custom is selected, the specified PYTHONPATH is used.

Setting this property is usually only necessary if your code changes sys.path at runtime in a way that Wing can't auto-detect or if it depends on PYTHONPATH being set from the outside. You should not add the Python standard library's PYTHONPATH entries here, since Wing will be able to obtain those by inspecting your selected Python Executable.

This property allows displaying the entered Python Path either as a list or as text using the path separator appropriate for the OS. If you need to paste in a path, select View as Text first and then right-click to Paste.

When using a container as the Python Executable, this property is disabled because Wing instead obtains the Python path from the container.

Python Options sets the command line options sent to the Python interpreter while debugging or executing code with this launch configuration. The default uses the setting in Project Properties. Using -u sets Python into unbuffered I/O mode, which ensures that the debug process output, including prompts shown for keyboard input, will appear in a timely fashion.

Note that these are not the command line arguments to send to your code, but instead options sent to Python itself. To send arguments to your code, set Run Arguments under the Environment tab.

Environment Tab

Run Arguments sets the command line arguments to send to code debugged or executed with this launch configuration. Wing does not interpret backslashes ('\') on the command line and passes them unchanged to the sub-process. The only exceptions to this rule are \' and \" (backslash followed by single or double quote), which allow inclusion of quotes inside quoted multi-word arguments.

Initial Directory selects the initial working directory to use for processes started with this launch configuration. By default this uses the Initial Directory specified in Project Properties. When Use default is selected, the directory of the launched file is used instead. When Custom is selected, the specified directory is used instead. Use ${WING:PROJECT_DIR} for the project's directory.

When using a container as the Python Executable, this property is disabled because Wing instead obtains the initial directory from the container.

Environment specifies environment variables that should be added, modified, or removed from the environment when using this launch configuration. The drop down menu selects the environment to modify: Add to inherited environment modifies the environment inherited when Wing was started, and Add to project values modifies the environment from Project Properties. When Use project values or Use inherited environment is chosen, any entered values are ignored and the selected environment is used without changes.

Each entry is in var=value form, without any quotes around the value, and must be specified one per line. An entry in the form var= (without a value) will remove the given variable so it is undefined.

Note that you are operating on the environment inherited by the IDE when it started (optionally, as modified in Project Properties) and not modifying an empty environment. On macOS the environment inherited by Wing may differ according to whether you launched Wing from the command line or with the Finder.

When using a container as the Python Executable, this property is disabled because Wing instead obtains the environment from the container.

Build Command sets a command that will be executed before starting debug with this launch configuration. This is useful to make sure that extension modules, Cython modules, and other compiled build targets are rebuilt before each run. The build is configured and run by the OS Commands tool.

Shared Launch Configurations

By default each launch configuration is stored in the project file. The Shared checkbox in the launch configuration dialog causes Wing to store that launch configuration in the Settings Directory instead, in a file named launch. Shared launch configurations are accessible from all projects.

Working on Different Machines or OSes

When the Shared checkbox is selected for a launch configuration, or when shared projects are used, launch configurations must be configured so that they will work across projects, machines, and operating systems.

For example, specifying a full path in the Python Path may not work on a different OS. The key to making this work is to use environment variable references in the form ${VARNAME} as described in Environment Variable Expansion. The referenced environment variables can be special environment variables defined by Wing, as in ${WING:PROJECT_DIR}, or user-defined values that are set either system-wide, or in Project Properties. Values set in Environment in Project Properties are by default not stored in the shared project file, so those may vary on each development machine.

A common example in configuring Python Path is to replace a full path like /Users/myname/src/project/src with ${WING:PROJECT_DIR}/src (this assumes you store the project in /Users/myname/src/project). In general, working off the project's location is a good approach to maintaining some independence from the configuration and disk layout on different development machines and OSes.

To make file paths work across OSes, use forward slashes instead of back slashes. The character sequence .. can be used to move up a directory on all OSes, as for example in {WING:PROJECT_DIR}/../libs/src.